Single-particle and collective motions from nuclear many-body correlation (PCM2025)

Towards the study of neutron-distribution in unstable nuclei through low-energy electron scattering

5 Mar 2025, 15:32

1m

Main Lecture Hall (University of Aizu)

Poster session

Speaker

Rika Danjo (Tohoku University, Research Center for Accelerator and Radioisotope Science)

Description

The charge density distributions of nuclei, ρ(r), are the best determined by elastic electron scattering, and those of the stable nuclei that have been studied so far have played an essential role in revealing their internal structure.

Recently, the 4th-order moment of the charge density distribution, $$, is shown to be a novel way to access neutron-distribution radius (ref.[1]).

Experimental determination of <r_c^4> can be performed by the two methods; 1) obtained from the ρ(r) derived from the form factor F(q) (where q is the momentum transfer) measured covering a wide q range (note that the electron scattering cross section has 1/q${^4}$ dependence), and 2) obtained via Taylor expansion of F(q) at low q region.

In the year 2023, the world’s first electron scattering for online-produced neutron-rich unstable nuclei has been successfully conducted at the SCRIT facility of RIKEN (ref. [2]). Here, it is interesting to point out that elastic electron scattering for unstable nuclei at low q region may allow access to the neutron-distribution radius of neutron-rich unstable nuclei using the method 2) as well as the proton-distribution radius.

In reality, F(q) cannot be obtained directly, instead we usually use ρ(r) from the cross section to calculate $$ . However, for the method 2), F(q) is essential. Therefore to use the method 2), we are proposing a new approach to extract <r_c^4> within the framework of Plane Wave Born Approximation (PWBA), but taking into account Coulomb distortion for the case of $^{208}$Pb as a benchmark. In addition to the theoretical approach, experimental verification is currently underway at the low energy facility (ULQ2) at RARiS, Tohoku University. In this talk, I will discuss the current status of this project and also the future possibilities at the SCRIT facility.

Reference
[1] H. Kurasawa and T. Suzuki, “The nth-order moment of the nuclear charge density and contribution from the neutrons”, Prog. Theor. Exp. Phys. 2019, 113D01(2019).
[2] K. Tsukada, “The first electron scattering has been successfully performed at the self-confining radioactive-isotope ion target (SCRIT)facility”, Phys. Rev. Lett. 131.092502(2023).

R. Danjo¹, T. Goke¹, Y. Honda¹, K. Hotta¹, C. Legris¹, Y. Maeda³, T. Muto¹, T. Ohnishi², H. Sakaguchi⁴, T. Suda¹, T. Suzuki¹, K. Tsukada$^{2,5}$, T. Yamauchi¹, K. Yoshimoto¹

1: Research Center for Accelerator and Radioisotope Science
2: Nishina Center for Accelerator-Based Science, RIKEN
3: Faculty of Engineering, Miyazaki University
4: Research Center for Nuclear Physics, Osaka University
5: Institute for Chemical Research, Kyoto University